For anthropologists, Africa was a point of exceptional diversity between 2 million and 1.5 million years ago. In both East and South Africa, the fossil record presents evidence of several different hominin species. Some fossils belong to our own genus, Homo, and others belong to robust australopithecines.
These two forms seem like they should be easy to tell apart. Robust australopithecines had extraordinarily large mandibles compared to living humans. Consider:
- The main part of the mandible, which holds the teeth, is called the mandibular corpus. In robust australopithecines, this is often extremely thick and tall, with a large distance from the inferior border of the mandible to the teeth.
- The portion of the mandible that extends upward to articulate with the temporal bone is called the mandibular ramus -- with one on both left and right sides. The mandibular ramus of many robust australopithecines is exceedingly tall, reflecting the very vertically tall faces of these hominins.
- Robust australopithecines have hugely expanded premolars and molars, and greatly reduced incisors and canines. Early Homo has overall larger teeth than in living humans, but the proportions between the molars, premolars, incisors and canines is very much like people today.
However, despite these obvious differences, the mandibles of early Homo and robust australopithecines are not always so easy to tell apart. This station has several mandibles from robust australopithecines, mainly from Australopithecus robustus from Swartkrans and Kromdraai, South Africa. There are also several mandibles of Homo erectus here, and a handful of mandibles that are likely early Homo but not definitely H. erectus.
Can you tell them apart? Try seriating these from most humanlike to most robust australpithecine-like. Is there a clear dividing line between the two, or are there questionable specimens?